Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net earnings	$ 19,829	$ 19,679	$ 38,612	$ 39,025
Other comprehensive (loss) income, net of tax:
Net foreign currency translation adjustment	(215)	(2,911)	(1,304)	(1,548)
Unrealized loss on cash flow hedge	(1,299)	0	(1,299)	0
Net change in postretirement benefit plans	6	16	11	29
Other comprehensive loss	(1,508)	(2,895)	(2,592)	(1,519)
Comprehensive income	$ 18,321	$ 16,784	$ 36,020	$ 37,506